Start-up investor Li Jiang just turned 30, and now he can’t stop thinking about his own mortality.

For Jiang, who’s based in San Francisco, living longer isn’t just about eating healthy and exercising regularly. Last month, he cryogenically froze his stem cells, in the hopes of someday injecting them back into his body.

Jiang is one of the earliest testers of Forever Labs, which extracts and stores young adults’ stem cells to potentially combat age-related illnesses like arthritis and heart disease. The company has the ambitious plan to counter “aging itself.”

Forever Labs is a graduate of the start-up accelerator program Y Combinator and has raised $2 million in funding to expand its service to more states. Jiang, a former investment banker who worked on health-care deals, is also an early investor in the start-up.

It’s not a cheap endeavor. Forever Labs charges $7,000 for a plan that includes the procedure and lifetime storage. Jiang says that’s the price tag for longevity.

“If you are able to extend your life by even five years, I mean I think you would pay something to do that,” he said.

But this is unprecedented work, and the market is so nascent that doctors and scientists are still researching how the frozen stem cells can even be used in the future.

Not everyone is convinced that it’s worth the time and money to store these cells.

Agnieszka Czechowicz, an assistant professor of medicine at Stanford focusing on stem cell transplantation, said it’s unclear if regulators will approve any potential therapies that would rely on these samples. There’s also the risk that the samples might not be large enough to be used in any meaningful way, and uncertainty about what would happen if Forever Labs were to fail, as many start-ups do.

Despite the many hurdles associated with private stem cell banking, Czechowicz said she’s excited about the prospects and “the evolving research that may open opportunities to use such cells.”

To perform the procedure on Jiang, Dr. Chad Roghair, a sports medicine practitioner, used an ultrasound to locate a bone in his hip. He then applied a local anesthetic to the small of Jiang’s back to numb the pain, before using a series of small drills and large needles to extract a combination of blood and bone marrow.

Forever Labs works with doctors like Roghair, who have experience extracting stem cells and an interest in regenerative medicine.

“Stem cells have tremendous potential,” Roghair told CNBC. “Currently in the musculoskeletal community, which I specialize in, we are using it to treat arthritis or degenerative conditions, but the practical application in other medical specialties is limitless.”

The procedure took about 15 minutes to complete and afterward, Jiang said all he felt was a bit of stiffness, along with some routine anxiety.

Forever Labs said it’s carried out dozens of procedures so far in a range of facilities, but declined to provide specific user numbers. Most of the early adopters are tech workers from the Bay Area or people in medicine, said CEO Steven Clausnitzer, who founded the company in 2015.

Clausnitzer said he started Forever Labs after speaking with stem cell scientists who wanted to bank their own cell but lacked any available options. While it’s now fairly common for parents to store an infant’s umbilical cord blood for future medical use, adults haven’t had similar resources for their own stem cells until recently.

For Clausnitzer, who banked his own cells three years ago, the possibility of using them in the future gives him peace of mind as he ages.

“I’m turning 41 in a couple of weeks,” he said. But, “my stem cells are 38.”